Tooth for excavating apparatus



| MAssA Filed Jan. 27 1942 INVENTOR fizz/eaves MAssA,

May 18, 1943 TOOTH FOR EXCAVATING APPARATUS ..O Q a Patented May 18, 1943 UNITED STATES PATENT OFFICE 2,319,464 'roo'rn FOR ExcAvArmG APPARATUS Laurence Massa, Los Angeles, Calif. Application January 2'7, 1942, Serial No. 428,405

4 Claims. (01. 37-142) This invention relates to excavating machinery or other devices for handling material. Machines used for excavating generally have a bucket or scoop which ha a sharpened lipfor scooping up the material being excavated. Some machines, such as ditchers andtrenchers, are

intended to produce an excavation of definite size, the width of the excavation being governed by the size of the series of scoops or buckets used to remove the material. Machines of this type are provided with teeth set around the cutting lips of the buckets. A the machine continues in service these teeth wear and become inefflcient as digging instruments. Furthermore, as the teeth wear down unduly the body of the bucket drags over the walls of the excavation. In addition to causing ineificient digging and wear upon the bucket, the shortenversible tip.

It is a further object of the present invention to provide a tooth having a removable tip which will stay in place without the use of auxiliary fastening devices.

It is a further object of the present invention to" provide a reversible tooth tip which will out after reversal along substantially the same line as the new tooth tip cut before reversal.

It is a further object of the present invention to provide a reversible tooth tip which will not entail substantial loss of gauge of a trench dug by a trencher upon reversal of the tip. a

It is a further object of the present invention to provide a tooth tip and holder which depend upon the engagement of a tapered shank in a tapered socket to hold the tip in place, which are in turn secured to the bucket, the tips being reversible after a certain amount of wear. However, all of the previous structures suffer from the disadvantage that when the teeth are worn reversed in their holders, such reversal places the new cutting edge of the teeth in such a position as to decrease the efflciency of the excavator as a whole, or else it causes the cutting of an undergauge trench in the case of machines for digging trenches or ditches.

In addition to the above disadvantages, machines which have removable and replaceable teeth, or reversible tips, either require a great deal of work in replacing these teeth or tips, or else the teeth are not efllciently held in place.

. For instance, the teeth may be held on the buckets by means of bolts, which require that two or more bolts be removed and replaced for every toothchanged, a time consuming operation in the case of a. ditcher having a large to such an extent as to warrant their tips being will not loosen under digging stress.

This invention possesses many other advantages and has other'objects which may be made more easily'apparent from a consideration of one embodiment of the invention. For this purpose there are shown two forms in the drawing accompanying and forming part of the present specification. These forms will now be described in detail, illustrating the general principles-of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring now to the drawing:

Figure 1 is a longitudinal section taken through a part of a bucket and a tooth mounted thereon;

Figure 2 is a view similar to that of Figure 1 showing the tip after it'has been worn and reversed in its holder;

Figure 3 is a section taken on line 33 of Figure 1; T

Figure 4 is a perspective view of the tip shown in Figures 1 and 3; and,

Figure 5 is a section similar to Figure 1 but of a modified form of construction.

As the present invention is adaptable to a wide range of d ifierent types of excavating equipment, and as it embodies principles which render it useful in all of these different types of equipment, a typical instance has been selected for illustration, but it is to be clearly understood that the selection of this particular construction is not intended to be limitative but illustrative only. For this purpose the tooth has been shown as constituting one of the side teeth of a trencher. Figure 1 shows, in addition to a portion of the bucket and the tooth, a line Ill-l which represents the wall of the trench produced. It can be seen that as the tip of the tooth wears down the wall I0 is produced to the right of the position shown in Figure 1. Obviously, this would result in an undergauge trench. Furthermore, in machines not intended to dig to gauge, moving of this line Ill to the right would result in the body of the bucket or the tip holder dragging on the unexcavated earth which eventually wears the bucket unduly, and furthermore renders digging difllcult and ultimately impossible. It is with the provision of means for preventing this change of the efiective cutting line of the tooth with which this invention deals. As the cutting progresses, the tooth has a motion through the material being out which has, in Figure l, a downward component. This downward component of motion wears the cutting edge of the tooth until the toothis worn to the dotted line ll (Figure 1). When the tooth is worn to such an extent the back surface H of the tooth sliding along the excavated wall interferes with the digging action. It is customary to replacethe tooth or otherwise provide a new cutting edge when the tooth reaches this condition. In the present instance this is done by simply reversing the tooth tip as shown in Figure 2. The edge 12 of the tooth tip then takes the position shown in Figure 2 and the back face H which formerly dragged along the excavated wall l0 then becomes the front cutting face of the tooth. It will be noted that the wall ID in Figure 2 is the same distance from the body of the bucket as wall 10 in Figure l. The relationship of the parts which permits this result is one of the important features of this invention. As shown in Figures 1 and 2, a tip holder I3 is secured to the body of the bucket and is provided with a tapered socket M for receiving the tip I. This socket is at an angle to the excavated wall It. For purposes of explanation, a center line I5 has been shown in Figure 1, this center line l5 being not the center line of the tooth as a whole but merely the center line of the socket M. The tip 16 is provided with a tapered shank H for 'entry into the socket. If the center line II and the edge I! have a certain relationship with the'wail In the edge I! will be placed against the wall l0 as the tooth tip is reversed. This relationship is best demonstrated by drawing a perpendicuiar to the center line I! through edge II. This perpendicular will intersect line Ill at point a and the center line at point b. If the distance a-b is equal to the distance between D and I2, reversal of the tip will place the edge I! at point a. Thus, upon reversal of the tip, the tooth will dig along line N), which is the desired effect of being in the order of a few inches only. However, when heavy equipment is used the tooth tip IE will be considerably thicker than that shown and thus this increase in gauge may be considerable.

In the shown device one method of achieving this relationship between the center line l5 and the edge l2 has been shown. The tapered shank ll of the tooth tip is formed by having one face Ila bevelled with respect to the rest of the tip while the opposite face of the shank is a continuation of the face of the tip. That is, the face l8 of the tip continues to the rear end of the shank while the face I9 is bevelled from the point 20 rearwardly to form a taper with the face ll. It can be appreciated that this singlebevelled surface to form a taper is merely an equivalent of bending the tooth at point 20. If desired the tapered shank may be set at other angles to the faces of the tip, depending on the thickness of the tooth, the amount of wear which will be tolerated before the tooth tip must be reversed, and other factors.

In securing tooth tips to holders by the use of tapered shanks and sockets, it has been found in the past that the tips have a tendency to work loose. Accordingly in devices utilizing tapered shanks and sockets auxiliary fastening devices have customarily been employedto secure the tips in place. I have found that the tendency of tapered shanks to work out of tapered sockets can be successfully overcome by the employment of tapered surfaces which are more, or less parallel to the direction ofmaximum stress tending to dislodge the tooth tip from its socket. In the present instance this maximum stress tending to dislodge the tooth tip naturally comes in a disuch reversal. It is to be understood that Just 7 before reversal the tooth will be digging along a line which is parallel to the line "I but to the right thereof, and passing'through the edge l2.

'The reversal thus increases the gauge of the rection best indicated by the arrows in Figure 1. This stress tends to bend the tooth tip, and, if ordinary tapered surfaces are used, will eventually cause the tip to work out of the socket. It, is to be understood that the tendency to bend the tip does not, perhaps, actually bend it, but the alternating forces set up nevertheless tend to loosen the tip shank from the socket. For this reason the engagement of the surfaces 22 and 23 of the socket andthe surfaces l8 and Ila of the shank are not particularly efficacious in holding the tip in place. Accordingly, in the drawings, the shank is shown as having its side edges formed with a taper. This taper is chiefly responsible for holding the tooth tip in place. I have also found that there is a definite range of tapers which may be utilized most satisfactorily in this connection. The most eflicient taper appears-to be in the order of 0.6 inch per foot, or a taper of 0.05. However, the range appears to be between 0.015 and 0.15. Within this range the frictional forces are so related that the tooth has no tendency to be displaced. This same taper may be applied to the front and back faces of the shank of the tooth tip.

The shown form of device with a bolted holder can be manufactured by modifying an existing tooth, the existing tooth being simply cut off and provided with a socket. If desired, the tooth may be made byproviding a special socket welded directly to the bucket. This type of construction is shown in Figure 5. A socket portion 30 is secured to the bucket 3| by welding or the like. In order to prevent the weld from interfering with the shank of the tip when the tip is inserted in the socket a flange 32 is made integral with the socket 30. This flange 32 prosaid support including means removably mount'-' ing said tip on said support for reversal by rotation about an axis at an angle to the path of movement of the'edge of said tip, the perpendicular distance from said axis to a predetermined point on the front face ofsaid tip being equal to the distance along the same perpendicular to the path of movement of the edge of said tip, whereby upon reversal of the tip after it has worn to produce a cutting edge at said predetermined point said cutting edge will be positioned in the path of movement of the original cutting edge.

2.'In a material handling device including a member movable through the material to be handled; a tooth comprising a support mounted on said member, an edged tooth tip, said tip and said support having cooperating shank and socket for securing said tip to said support, the axis of said socket being at an angleto the path of movement of the edge of said tip, the perpendicular distance from said axis to a predetermined point on the front face of said tip being equal to the distance along the same perpendicular from the axis to the path of movement of the edge of said tip, whereby upon reversal of the ,tip after it has worn to produce a cutting edge at said predetermined point, said cutting edge will be positioned in the path of movement of the original cutting edge. e

3. In a material handling device including a member movable through the material to be handled; a tooth comprising a support mounted on said member having a socket, a tooth tip having a cutting edge and a shank for cooperative engagement with the socket in said support, the axis of said socket being at an angle to the path of movement of the edge of the tip, the perpendicular distance from theaxis of the socket to a predetermined point on the front face of said tip being equal to the distance along the same perpendicular to the path of movement of the edge of the tip', whereby upon reversal of the tip after it has worn to produce a cutting edge at said predetermined point said cutting edge will be positioned in the path of movement of the original cutting edge.

4. In a material handling device including a member movable through the material to be handled; a tooth comprising a support mounted on said member having a tapered socket, a tooth .tip having a cutting edge and atapered shank,

the taper on said shank being formed by a bevel on the rear face of said tip, the axis of said socket being at an angle to the path of movement of the edge of the tip, the perpendicular distance from the axis of the socket to a predetermined point on the front face of said tip being equal to the distance along the same perpendicular to the path of movement of the edge of the tip, whereby upon reversal of thetip after it has worn to produce a cutting edge at said point, said cutting edge will-be positioned in the path of movement of the original cutting edge.

LAURENCE MASSA. 

